Frame and yoke assembly for high-speed printers and method of making same

ABSTRACT

A method of making the frame and yoke of a high-speed printer, comprising stamping out a number of identical pieces, each conforming in shape to the side frames or the yoke frames of the printer to be completed but of thinner material, in which locating holes for the working parts of the printer are stamped in the same operation; bonding sets of the stamped parts together to form main frames and yoke frames of the desired final thickness, boring or grinding the holes that must be precisely located in a jig to desired final dimensions, and mounting the bonded frames together by framing members located with dowels installed in the holes provided in the side frames and precision bored as described.

United States Patent 2,040,152 5/1936 Pennington lnventor Melvin L. Litvin Chestnut Hill, Mass Appl. No. 823,022

Filed May 8, 1969 Patented Aug. 17, 1971 Assignee Data Printer Corp.

Boston, Mass FRAME AND YOKE ASSEMBLY FOR HIGH-SPEED PRINTERS AND METHOD OF MAKING SAME 7 Claims, 1 Drawing Fig.

29/445, 29/481, 101/93 R in c1. B23q 17/00 FieldolSearch 29/407,

References Cited UNITED STATES PATENTS 2,479,023 8/1949 Peyrebrune et a1 1. 29/407 X 3,267,561 8/1966 Richer etal. 29/445X 3,499,382 3/1970 Potter et al. 197/186 X ABSTRACT: A method of making the frame and yoke of a high-speed printer, comprisingstamping out a number of identical pieces, each conforming in shape to the side frames or the yoke frames of the printer to be completed but of thinner material, in which locating holes for the working parts of the printer are stamped in the same operation; bonding sets of the stamped parts together to form main frames and yoke frames of the desired final thickness, boring or grinding the holes that must be precisely located in a jig to desired final dimensions, and mounting the bonded frames together by framing members located with dowels installed in the holes provided in the side frames and precision bored as described.

PATENTED. Mm 1 ml INVENI'OR.

LVIN LITV'N FRAME AND YOKE ASSEMBLY FOR HIGH-SPEED PRINTERS AND METHOD OF MAKING SAME My invention relates to high-speed printers, and particularly to a novel method of making the main frames and yoke frames of a high-speed printer.

Since at least 1950, large numbers of high-speed printers of the line-at-a-time type have been made and used. Though the construction of these machines has varied in some respects, in other respects the construction, and the method of manufacturing, such printers has remained essentially. the same for almost years. In particular, the method of making the basic frame, upon which the print head and associated electronics are assembled is essentially the same today as it was when the first printers were made. The requirements of the frame of a high-speed printer are dictated by the need to produce copy at high line rates with good print quality, involving both uniform image density and accurate alignment of the character images on the printed sheet. For that purpose, the parts of the printer must be be very accurately located relative to each other and to the line of print, and large amounts of energy must be dissipated without undue vibration that would tend to cause random misalignment and malfunction of the parts. The drive assembly, print roll and paper feed mechanism require strong, accurately located bearing supports. For these reasons, the printer frames have commonly been made form solid heavy sheet metal stock, of such materials as cast steel, cast aluminum, and the like. Such sheets must be machined to size, and then accurately drilled and bored in a jig or other fixture to locate the mounting holes for printing apparatus, so that when that apparatus is installed, it is in position and alignment. The necessary machining operations are complex, time consuming and expensive, but have always been considered a necessary part of the price that must be paid for acceptable print quality at the high line rates that are desired. The object of my invention is to simplify the construction of frames for high-speed printers, without sacrificing the qualities of ruggedness, weight and accuracy that are essential to proper performance.

Briefly, the above and other objects of my invention are accomplished by a novel method of manufacturing the frame structure of a high-speed printer which relies heavily on diestamping for producing frame elements. When stamped, the frame elements have the configuration, and most of the dimensions, required in the final product. The time and effort that formerly went into the manufacturing of a single sideplate is, in accordance with my invention, devoted to the preparation of the die from which many properly dimensional parts can be produced. In order to retain the weight, support area and rigidity required, the stamped parts are laminated and bonded together, as by welding, brazing, bolting, riveting, ce-

menting, doweling or the like, to form frame parts of the required thickness. All of the holes required for mounting shafts or hearings, or for clearance for cables and the like, are produced in the stamping operation. Those which do not require precisely locating, such as cable clearance holes, are finished in the stamping operation. Those holes, such as bearing supports, which must be very precisely located and dimensioned, are then dressed down by boring or grinding in a jig, after lamination and bonding of the frame elements. Considerably less effort is required for that operation because most of the metal is removed in the stamping operation. The side frames are provided with locating holes, which are finished to close tolerances in the manner just described, and which receive dowels for accurately locating the crossmembers that tie the side frames together. The principal crossmembers comprise a tie bar and a print-head-mounting frame mutually disposed at an angle and extending between the side frames. The print-head-mounting frame is preferably of heavy cast iron, and constitutes a substantial proportion of the weight of the frame. Location of the weight in this area is preferred because it makes it possible to minimize vibration caused by actuation of the print hammers by increasing the inertia of the hammer support assembly relative to the The process of my invention, and the apparatus produced thereby, will best be understood in the light of the following detailed description, together with the accompanying drawing of a preferred embodiment thereof.

Referring to the drawing, the sole FIGURE comprises a schematic perspective sketch of a high-speed printer frame and yoke assembly constructed in accordance with the method of my invention.

In the drawing, I have shown the main frame and yoke frame assembly of a high-speed printer constructed in accordance with my invention. The apparatus generally comprises a pair of side frames 1 and 2 connected together by a print-head-mounting frame 3 and a tie bar 4. On the side frame 1 is pivotally mounted a yoke frame 5, and on tee side frame 2 is pivotally mounted a corresponding yoke frame 6. The yoke frames 5 and 6 are rigidly secured together by means of a pair of aluminum extrusions 7 and 8 which also form a shroud for the print roll, and serve as a ribbon guide.

In manufacturing the apparatus shown in the drawing, in accordance with my invention, stamping dies are first made to the configuration of the side frames 1 and 2 and the yoke frames 5 and 6. Considering the side frame 1, these dies produce a pair of plates 8 and 9 which are each of the same configuration and each half the thickness of the required side frames.

In addition to the outer configuration of these plates 8 and 9, the die preferably provides for punching out the various apertures that will be required in the final frame. Specifically, notch 10 is provided at the rear of the frame to receive bolts which secure the tie bar 4. The tie bar may be a steel block having a length determined by the number of columns that the printer is to produce, a width of 3 to 4 inches, and a thickness of three-eights of an inch. In order to locate the tie bar 4 accurately relatively to the frame members 1 and 2, each of the plates 8 and 9, and the corresponding plates 18 and 19 from which the frame 2 are made, are punched with two dowel holes 12 and 13.

A number of cable clearance holes 14 are provided at points convenient for the passage of electrical cables. Holes 15 are provided to receive a jackshaft forming a conventional part of the drive mechanism of the printer, and cutouts 16 are provided in the plates 8 and 9 to receive the drive motor of the printer. Corresponding cutouts 17 on the opposite pair of plates 18 and 19 forming the side plate 2 are provided to accept the clutch-brake assembly that is also a conventional portion of the drive system of a high-speed printer.

Adjustment slots such as 18 are provided in these cutouts so that the belt tension and the exact positions of the motor, the clutch-brake, and the shafts and pulleys driven thereby can precision machining adjusted without requiring precision machining of the cutouts l6 and 17.A pair of dowel holes 21 and 22 are punched in each of the plates 8, 9, 18 and 19 to receive dowels that will serve to locate the print-head-mounting plate 3.

Clearance holes are also provided to accept bolts 23 for securing the side frames to the base frame 3. Holes 24 are punched in to accept the bearings of a latch shaft assembly for securing the yoke to the frame when the yoke is in operating position. Holes 30 are provided to receive the bearings for the paper feed tractor shaft.

The yoke frames 5 and 6 are preferably made of three laminations, such as the sheets 25, 26 and 27 forming the yoke frame 5. The number of laminations used is determined by the diameter of the smallest hole to be punched, which diameter should not be less than the thickness of each lamination for proper stamping.

In the stamping operation, the laminations forming the frames 5 and 6 are formed with slots 28 that serve cooperate with stop pins 29 mounted on the side frames to limit the movement of the yoke relative to the frame to a desired amount. Holes 31 are provided in the yoke frames 5 and 6 to receive the bearings for the print roll. Holes 33 and 34 are provided in the frame 6 to receive the bearing supports for the mandrels that carry the printing ribbon. Corresponding holes are not needed in the frame 5, but it is convenient to make both frames with the same die. Miscellaneous additional holes, as at 35, may be provided to suit the needs of a particular construction. Holes 38 are provided to locate and mount the ribbon guides 7 and 8.

The frame and yoke plates are provided with registering holes to receive pivot pins. Thus, the holes such as 36 in the frame 5 receive pivot pins such as that shown at 37 for the opposite side.

After the frame parts thus described have been stamped, they are bonded together, as by spot welding, brazing, riveting, bolting, or the like. The holes that are not critical, such as the cable clearance holes 14 and the'cutouts 16 and 17, are now finished. The holes such as the dowel locating holes 21, 22, 12 and 13, and the shaft bearing receiving holes such as 14 and 31, that do require precise location and finishing, are jig bored to the desired centers and diameters. That operation is relatively simple because most of the metal has already been removed.

The ribbon guides 7 and 8 are preferably made by extruding aluminum, as that is a very convenient way to obtain the complex shapes required. To allow for some tolerance in the length of the guides 7 and 8, the yoke frame 6 is fixed axially with respect to its pivot 37, whereas the frame 5 is allowed to float axially on its pivot to allow the guides 7 and 8 to determine the exact spacing between the yokes.

While I have described my invention with respect to the details of a preferred mode of carrying it out, many changes and variations will occur to those skilled in the art upon reading my description, and such can obviously be made without departing from the scope of my invention.

Having thus described my invention, what I claim is:

1. The method of making tee frame of a high-speed printer, comprising:

the steps of die stamping a set of at least four frame elements from sheet metal of thickness with adie formed to punch a set of locating holes, said locating holes having a diameter at least equal to t,

placing at least two of said frame elements in registration to form a first frame assembly,

placing the rest of said frame elements in registration to form a second frame assembly,

connecting the elements of said first frame assembly together side-by-side in parallel registration,

connecting the elements of said second frame assembly together side-by-side in parallel registration,

boring said locating holes to predetermined centers and diameters,

forming locating holes in a crosspiece corresponding in spacing and diameter to pairs of locating holes in said first and second frame assemblies,

registering said crosspiece between said frame assemblies with dowels inserted in said locating holes, and connecting said frame assemblies to said crosspiece with said dowels in position.

2. The method of claim 1, further comprising:

the steps of forming locating holes in a second crosspiece;

and,

in the course of stamping said frame pieces, stamping additional locating holes corresponding to the locating holes in said second crosspiece, and

stamping clearance holes in position to register with said crosspiece when said additional holes are in registry with the locating holes in said second crosspiece, and

finishing said additional locating holes to predetermined centers and diameters after said frame pieces are connected together;

locating said second crosspiece between said frames with dowels inserted in said additional locating holes and thence into the locating holes in said second crosspiece;

said locating holes being disposed to locate the crosspiece at an acute angle to each other. 3. The method of making the frame of a high-speed printer, comprising? the steps of stamping a series of at least four identical side frame pieces from sheet metal of thickness t, where t is not greater than twice the smallest radius to be stamped, and in tee stamping operation stamping out a pair of locating holes adapted to register with corresponding locating hol s' formed in a crosspiece to be used to join the frames, 1 a plurality of clearance holes for admitting fasteners to secure the frames to the crosspiece, and a plurality of bearing support holes for receiving shaft bearings, connecting at least two of said stamped frame pieces together in parallel side-by-side registry to form a first side frame, connecting the rest of said stamped frame pieces together in similar registry to form a second side frame, finishing said locating holes and said bearing support holes to predetermined centers and diameters, forming locating holes matching said locating holes in the ends of a crosspiece, locating said frames in registry with said crosspiece with dowels placed in said locating holes, and connecting said frames to said crosspiece with fasteners passing through said clearance holes with said dowels in position. 4. The method of claim 3, further comprising: the steps of stamping a set of at least four yoke frame pieces from sheet metal of thickness t, where t is no greater than the smallest diameter to be stamped, and in the course of said stamping, stamping a hole to receive a print roll bearing, a hole to receive a pivot pin, and I a plurality of holes to receive fasteners to secure a ribbon guide between the yoke frames, and in the course of stamping said side frame pieces, stamping a hole to receive a pivot pin, and, after connecting said side frame pieces together, finishing said pivot pinholes to predetermined centers and diameters; connecting the rest of said yoke frame pieces together in parallel side-by-side registry to form a second yoke frame; finishing said holes in said yoke frames to predetermine centers and diameters; connecting said first yoke frame to one end of a ribbon guide; mounting said yoke frames on said side frames with pivot pins extending through said pivot pinholes in said yoke and side frames; and fastening said second yoke frame to the other end of said ribbon guide. 5. The method of making the yoke frame of a high-speed printer, comprising:

the steps of stamping a set of at least four yoke frame pieces from sheet metal of thickness t,'where t is no greater than the smallest diameter to be stamped, and, in the course of said stamping, stamping a hole to receive a print roll bearing, a hole to receive a pivot pin, and a plurality of holes to receive fasteners to secure a ribbon guide between the yoke frames, connecting at least two of said frame pieces together in parallel side-by-side registry to form a first yoke frame, connecting the rest of said frame pieces together in parallel side-by-side registry to form a second yoke frame, finishing said holes to predetermined centers and diameters, and connecting said yoke frames to opposed ends of a crosspiece with fasteners passing through said fastener-receiving holes. 6. The method of making the side frame of a high-speed printer, comprising:

then

finishing said locating and shaft mounting holes to predetermined diameters.

7. The method of claim 6, in which at least two laminations of thickness 1 are stamped out and connected together, where t is not greater than the diameter of the smallest hole to be stamped and at least 2! is the desired thickness of the finished frame. 

1. The method of making tee frame of a high-speed printer, comprising: the steps of die stamping a set of at least four frame elements from sheet metal of thickness t with a die formed to punch a set of locating holes, said locating holes having a diameter at least equal to t, placing at least two of said frame elements in registration to form a first frame assembly, placing the rest of said frame elements in registration to form a seconD frame assembly, connecting the elements of said first frame assembly together side-by-side in parallel registration, connecting the elements of said second frame assembly together side-by-side in parallel registration, boring said locating holes to predetermined centers and diameters, forming locating holes in a crosspiece corresponding in spacing and diameter to pairs of locating holes in said first and second frame assemblies, registering said crosspiece between said frame assemblies with dowels inserted in said locating holes, and connecting said frame assemblies to said crosspiece with said dowels in position.
 2. The method of claim 1, further comprising: the steps of forming locating holes in a second crosspiece; and, in the course of stamping said frame pieces, stamping additional locating holes corresponding to the locating holes in said second crosspiece, and stamping clearance holes in position to register with said crosspiece when said additional holes are in registry with the locating holes in said second crosspiece, and finishing said additional locating holes to predetermined centers and diameters after said frame pieces are connected together; locating said second crosspiece between said frames with dowels inserted in said additional locating holes and thence into the locating holes in said second crosspiece; said locating holes being disposed to locate the crosspiece at an acute angle to each other.
 3. The method of making the frame of a high-speed printer, comprising: the steps of stamping a series of at least four identical side frame pieces from sheet metal of thickness t, where t is not greater than twice the smallest radius to be stamped, and in tee stamping operation stamping out a pair of locating holes adapted to register with corresponding locating holes formed in a crosspiece to be used to join the frames, a plurality of clearance holes for admitting fasteners to secure the frames to the crosspiece, and a plurality of bearing support holes for receiving shaft bearings, connecting at least two of said stamped frame pieces together in parallel side-by-side registry to form a first side frame, connecting the rest of said stamped frame pieces together in similar registry to form a second side frame, finishing said locating holes and said bearing support holes to predetermined centers and diameters, forming locating holes matching said locating holes in the ends of a crosspiece, locating said frames in registry with said crosspiece with dowels placed in said locating holes, and connecting said frames to said crosspiece with fasteners passing through said clearance holes with said dowels in position.
 4. The method of claim 3, further comprising: the steps of stamping a set of at least four yoke frame pieces from sheet metal of thickness t, where t is no greater than the smallest diameter to be stamped, and in the course of said stamping, stamping a hole to receive a print roll bearing, a hole to receive a pivot pin, and a plurality of holes to receive fasteners to secure a ribbon guide between the yoke frames, and in the course of stamping said side frame pieces, stamping a hole to receive a pivot pin, and, after connecting said side frame pieces together, finishing said pivot pinholes to predetermined centers and diameters; connecting the rest of said yoke frame pieces together in parallel side-by-side registry to form a second yoke frame; finishing said holes in said yoke frames to predetermine centers and diameters; connecting said first yoke frame to one end of a ribbon guide; mounting said yoke frames on said side frames with pivot pins extending through said pivot pinholes in said yoke and side frames; and fastening said second yoke frame to the other end of said ribbon guide.
 5. The method of making the yoke frame of a high-speed printer, comprising: The steps of stamping a set of at least four yoke frame pieces from sheet metal of thickness t, where t is no greater than the smallest diameter to be stamped, and, in the course of said stamping, stamping a hole to receive a print roll bearing, a hole to receive a pivot pin, and a plurality of holes to receive fasteners to secure a ribbon guide between the yoke frames, connecting at least two of said frame pieces together in parallel side-by-side registry to form a first yoke frame, connecting the rest of said frame pieces together in parallel side-by-side registry to form a second yoke frame, finishing said holes to predetermined centers and diameters, and connecting said yoke frames to opposed ends of a crosspiece with fasteners passing through said fastener-receiving holes.
 6. The method of making the side frame of a high-speed printer, comprising: the steps of stamping out a set of laminations each having the outer configuration of the frame to be made and within the outer configuration forming apertures comprising a set of locating holes, a set of shaft mounting holes, and a set of clearance holes for receiving fasteners, connecting said laminations together in side-by-side parallel registry to form a frame with said apertures in registry, then finishing said locating and shaft mounting holes to predetermined diameters.
 7. The method of claim 6, in which at least two laminations of thickness t are stamped out and connected together, where t is not greater than the diameter of the smallest hole to be stamped and at least 2t is the desired thickness of the finished frame. 